This invention relates to transistor circuits having a floating active element and, more particularly, to a floating field-effect transistor (FET) constructed with interchangeable source and drain regions.
Balanced circuit configurations, such as push-pull amplifiers, are well known. Such circuits generally employ paired active elements operating in dual channels and connecting with a balun, such as a transformer or differential amplifier, which combines signals of the two channels to produce a single output signal. The two channels with the paired active elements are employed because, as a general rule, active elements such as transistors operate effectively for current flow in only one direction. The transistors have been constructed to optimize the characteristics of the specific terminals, such as source and drain or emitter and collector for current flow in a preset direction.
The use of paired transistors, such as a type n-p-n and type p-n-p transistors, by way of example, in respective ones of the channels of the balanced circuit tends to compensate for the lack of symmetry in the characteristics of the individual transistors for improved operation of the balanced circuit. Symmetrical characteristics, as used herein, refers to interchangeability of source and drain regions or emitter and collector regions in a transistor upon a change in the polarity of the gate or base voltage.
A problem arises in that the use of paired transistors in dual channel balanced circuits to compensate for the lack of symmetry in the transistor characteristics introduces excessive complexity to the circuitry. In addition, such balanced circuitry does not have as much flexibility for use in a variety of circuit functions as could be accomplished if the transistor characteristics were fully symmetrical.